a) Field of the Invention
The invention is directed to a method and a device for target seeking for geodetic devices, especially tachymeters and theodolites.
b) Description of the Related Art
Tracking devices for tracking a reflector used as a target are known from geodetic devices, especially for tachymeters, wherein these tracking devices are capable of tracking a reflector located in the field of view of the telescope of a geodetic device. Target seeking outside of this field of view is accordingly possible only to a very limited degree. Devices of the type mentioned above are described, for example, in EP 465 584; JP 5-322 569 and DE 195 28 465.
A device for the sighting of a tachymeter from a reflector position is known from DD 156 029. The reflector can be found by transmitting the corresponding angles from the reflector position via radio to a base station in which the tachymeter is located and adjusting the complementary angle at the tachymeter. However, this device is very complicated technically.
Other devices make use of vertically or horizontally fanned out laser pulses which are emitted by the geodetic devices, e.g., theodolites. When the reflector arranged at the target station is hit during the movement around the standing axis or trunnion axis, a signal is generated by a photodiode arranged in the telescope of the theodolite, by means of which signal the drive of the telescope is stopped. A disadvantage in this device consists in that the rotating speed is limited by the pulse repetition frequency and that the system reacts to all reflectors located in the field of view of the telescope, e.g., also reflecting foils, rear reflectors of vehicles or the like objects.
A device of the kind mentioned above is known from the surveying periodical, "Photogrammetrie und Kulturtechnik", 1991, issue 8, pages 427 to 431.
Further, a sighting method for theodolites is known from DD 277 965, wherein, after a visual sighting of the target station with the theodolite, the actual angle measurement is carried out in that an active target beam is emitted by the theodolite and received by an active receiver at the target station. When the precise sighting is acquired, the rotation of the theodolite is stopped.